<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- 相对路径不可靠 -->
    <link rel="stylesheet" href="./css/app.css">
    <!-- 绝对路径  -->
    <!-- <link rel="stylesheet" href="/css/app.css"> -->
</head>
<body>
    <h2>首页</h2>
</body>
</html>